1. Field of the Invention
This invention relates to therapeutically treating and/or evaluating musculoskeletal injuries by ultrasound and, more particularly, to a gel containment structure.
2. Description of Related Art
The use of ultrasound to therapeutically treat and evaluate bone injuries is known. Application of ultrasound of appropriate parameters in suitable dosages at a proper external location adjacent a bone injury accelerates natural healing with few or no adverse side effects. For patients with reduced healing capacity, such as many elderly persons, ultrasonic therapy may promote healing of bone injuries that would otherwise require prosthetic replacement or leave the patient permanently disabled.
U.S. Pat. No. 4,530,360 to Duane ("Duarte") describes a basic therapeutic technique and apparatus for applying ultrasonic pulses from an operative surface placed on the skin at a location adjacent a bone injury. The "operative surface" of an ultrasonic delivery system, as that term is used in this application, is the exposed tangible surface of the system that transmits the ultrasonic pulses into the surroundings. For some systems the operative surface may be the transducer surface itself, while in others it may be a surface layer on top of the transducer surface. Duarte gives a range of RF signals for creating the ultrasound, ultrasound power density levels, a range of duration for each ultrasonic pulse, and a range of ultrasonic pulse frequencies. The length of daily treatment is described.
U.S. Pat. Nos. 5,003,965 and 5,186,162 both to Talish and Lifshey ("Talish '965" and "Talish '162," respectively) describe an ultrasonic delivery system where the RF generator and operative surface are both part of a modular applicator unit that is placed adjacent the skin location. The signals controlling the duration of ultrasonic pulses and the pulse repetition frequency are generated apart from the applicator unit. Talish '965 and Talish '162 also describes fixture apparatus for attaching the applicator unit so that the operative surface is adjacent the skin location. In Talish '965 and Talish '162, the skin is surrounded by a cast, while in U.S. Pat. No. 5,211,160 to Talish and Lifshey ("Talish '160") fixture apparatus is described for mounting on uncovered body parts (i.e., without a cast or other medical wrapping). Talish '160 also describes various improvements to the applicator unit.
It is known in the art that ultrasonic pulses attenuate rapidly in gases, such as air, and that, consequently, propagation of the ultrasonic pulses from the operative surface to the injury must be through a medium comprised of solids and liquids in order for the ultrasonic pulses to be efficiently transmitted. Since it is often not possible to press the operative surface completely flush against the external skin location corresponding to an internal injury, ultrasonically conductive coupling gel (hereinafter referred to as "coupling gel") is used between the operative surface and the skin to ensure a continuous contact. In fact, more recent systems implement a small zone between the operative surface and the skin for the coupling gel, thereby excluding any direct contact between the operative surface and the skin. Talish '162 describes such a system.
Duarte, Talish '965, Talish '162 and Talish '160 are all incorporated into this application by reference.
While the systems described in these references, and others, disclose the underlying therapeutic method and apparatus to one skilled in the art, they do not disclose a way of completely containing the coupling gel to the region between the skin and the operative surface. Previously, the coupling gel was often simply placed onto the operative surface. When the operative surface and the skin were brought together for treatment, the gel squeezed out into neighboring regions. This is especially undesirable when the ultrasonic treatment is delivered through an opening in a medical wrapping, such as a cast, because the gel soils the adjacent interior portions of medical wrapping.
Other systems contain the gel, but imperfectly. For example, in the system described in Talish '162, the gel is injected into a small zone created by a circumferential lip formation between the operative surface and the skin. Even in this system, however, gel squeezes between the lip and the skin when excess gel is injected to ensure the zone is completely filled.
It is therefore an objective of this invention to provide apparatus for containing the coupling gel substantially to the interface between the operative surface and the skin.